Adds update on injuries in paragraph 2, witness comments in paragraphs 6-7, GE declined to comment in paragraph 10

By David Shepardson

WASHINGTON, March 13 (Reuters) - An engine on an American Airlines AAL.O jet caught fire after the plane diverted to Denver on Thursday, forcing the evacuation of passengers using emergency slides, the Federal Aviation Administration said.

The airline said all 172 passengers and six crew members had exited the plane, though Denver International Airport said 12 people were transported to hospitals with minor injuries.

American Airlines Flight 1006 from Colorado Springs on a Boeing BA.N 737-800 landed in Denver around 5:15 p.m. (2315 GMT), diverting from its planned destination of Dallas after the crew reported engine vibrations, the FAA said.

Several dramatic videos of passengers standing on the wing of the plane as smoke poured out of the engine were posted on social media.

American Airlines said the plane had landed safely and taxied to the gate when it experienced an "engine-related issue."

“We were near (gate) B44, just landed from Pittsburgh. We stopped by the windows for a second and saw a flash of sudden fire, followed by a ton of smoke," said witness Aaron Clark.

"The fire was very brief and looked like it was extinguished pretty quickly by ground crews. The smoke continued for a while and that's when we saw people starting to exit from the rear slides."

The plane, which is 13 years old according to flight tracking website FlightRadar24, was equipped with two CFM56 engines manufactured by CFM International, a joint venture between GE GE.N and Safran SAF.PA.

The FAA said it would investigate the incident. A Denver International Airport spokesperson said the fire had been extinguished and flight operations had continued as normal.

Boeing and GE declined to comment.

The engine fire is the latest in a series of high-profile aviation incidents that have raised questions about U.S. aviation safety, including the January 29 mid-air collision of an American Airlines regional jet and an Army helicopter that killed 67 people.

Last month, a Delta Air Lines DAL.N regional jet flipped upside down upon landing at Canada's Toronto Pearson Airport in windy weather following a snowstorm, injuring 18 of the 80 people on board, though all passengers and crew members survived the incident.

American Airlines CEO Robert Isom and Delta CEO Ed Bastian on Tuesday cited recent air crashes and weather events as contributing factors to dampening U.S. travel demand, alongside mounting economic uncertainty.

(Reporting by David Shepardson and Kanishka Singh in Washington; Additional reporting by Dan Catchpole in Seattle, Rajesh Kumar Singh in Chicago and Lisa Barrington in Seoul; Editing by Jamie Freed and Tom Hogue)

((Kanishka.Singh@thomsonreuters.com; +12024508248;))